This section is intended to introduce the reader to various aspects of the art that may be related to various aspects of the present invention. The following discussion is intended to provide information to facilitate a better understanding of the present invention. Accordingly, it should be understood that statements in the following discussion are to be read in this light, and not as admissions of prior art.
Policy and Charging Control (PCC) architecture permits to integrate both policy and charging control. The architecture that supports Policy and Charging Control functionality is shown in FIG. 1. FIG. 1 has been taken from TS 23.203 (V.8.3.1) that specifies the PCC functionality for Evolved 3GPP Packet Switched domain, including both 3GPP accesses (GERAN/UTRAN/E-UTRAN) and Non-3GPP accesses. FIG. 1 shows a policy and charging control architecture.
SAPC (Ericsson realization of PCRF) supports an extension of 3GPP Gx protocol, called Gx+ that includes among other functionalities an additional policy control based on accumulated usage (Fair Usage Control). Fair Usage Control functionality allows changing the QoS setting or other settings such as service authorization information per subscriber based on actual use in terms of volume, time and events with reference to specific subscriber quotas. It also permits to change the QoS on a session in progress. The Fair Usage Control functionality is based on two functions:                Control of reporting function: PCRF indicates to PCEF when the reporting of usage is to be done, this is done by setting “quotas”. PCRF indicates to PCEF a “quota” for volume and/or time. When one of these quotas is empty PCEF reports the usage for all the reporting groups that are active for the IP-CAN session since the last report and also the usage for the entire IP-CAN session since the last report.        The reported usage is accumulated in PCRF per reporting group and a total usage. PCRF uses this accumulated usage to perform the Control Actions.        Control Actions: The control actions are the result of the policy evaluation of types Access & Charging Control and/or QoS Control in PCRF.        FIGS. 2 and 3 show some use cases for QBAU functionality. FIG. 2 shows Fair Usage Control use case message flow.        
When PCRF is working in a Geographical Redundancy configuration, there are two PCRF nodes, one is the “active” node (PCRF1) and the other is the “standby” node (PCRF2). The active node is the entry point of PCEF requests, and the standby node maintains its local database updated with replicated data from the active node. When the “active” node fails (PCRF1) the node that is in standby (PCRF2) starts to give service and becomes the “active” node. This is called a switch-over.
One problem in current solution in PCRF Geographical Redundancy (hereinafter GeoRed) configuration is that the standby zone is not aware of the usage accumulated in the active zone. For this reason, when the standby zone starts giving service, the quota information provided to the user is not updated.
An additional and more important problem in PCRF GeoRed configuration is that the standby zone is not aware of IP-CAN session data in the active zone. This means that if PCRF1 is giving service to the PCEF and it suffers a fail-over to PCRF2, when PCRF2 receives an authorization request from the PCEF, the request would be rejected because PCRF2 does not have information regarding the IP-CAN session that was established with the PCRF1. The consequence of rejecting the request is that the IP-CAN session is deactivated or that the PCEF uses local policies for the IP-CAN session. Both alternatives have a negative effect on the operator needs and the user experience. FIG. 3 depicts this problem with more detail. FIG. 3 shows handling unknown sessions in PCRF GeoRed configuration.
In steps 1-6 the PCEF has a running IP-CAN session established with the PCRF1. If PCRF1 fails, the PCRF2 takes the control.
If a CCR-Update message corresponding to this previously established IP-CAN session is received in PCRF2, as this node ignores the IP-CAN session data, the received sessionId in CCR-Update is unknown for the node, and PCRF2 returns the error code DIAMETER_UNKNOWN_SESSION_ID in the answer message.
Accordingly, a standby PCRF becoming active PCRF in GeoRed configuration can not provide an effective policy and charging control based on accumulated usage. PCEF node receives an error code for an established session, and consequently PCEF stops serving the user session. It should be noted that MSCC is the AVP used to report usage in CCR messages, and quota assigned in CCA messages.